Compressor regulator



C. 8. BAKER COMPRESSOR REGULATOR V 2 Sheets-Sheet 1 HIS- ATTORNEY Filed March 20, 1939 Dec. 24, 1940. v 1 BAKER L 2,225,854

COMPRESSOR REGULATOR Filed March 20, 1939 2 Sheets-Shegt 2 12.3 129 E1 112? I 11.5" 11117 109 12a" 94 93 l J i INVENTOR Mia: 52 Baker- HIS ATTORNEY Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE COMPRESSOR REGULATOR Application March 20, 1939, Serial No. 262,836

19 Claims.

This invention relates to regulators for motor driven fluid compressors and, more particularly, to a three-speed regulator which will make the speed of the motor conform generally to the required output of the compressor.

The type of portable compressor unit with which the regulator of the present invention is to be employed usually comprises a fluid compressor,

and an. internal combustion engine to drive the compressor. In the operation of such a. compressor unit heretofore the compressor delivered fluid under pressure to a receiver tank until a high fluid pressure was built up in the receiver. Upon the occurrence of this pressure a device provided on the compressor would stop. the discharge of fluid from the compressor to the receiver tank (commonly termed unloading) by throttling the amount of fluid supplied to the compressor and, at the same time, reduce the engine speed to the minimum rated speed. The unit would then continue to function in this manner until the pressure of the fluid in the respeed to supply the demand which made the op- 1;; eration of the unit uneconomical.

Accordingly, it is an object of this invention to provide means whereby the speed of the compressor unit is changed in accordance with the load demand to provide economical operation of the unit.

It is another object of the present invention to provide means whereby the compressor unit may be loaded and unloaded While the motor is operat ng at minimum speed.

A further object is to provide means whereby the unit may operate at an intermediate speed under certain load conditions instead of constantly accelerating to a maximum. speed and then decelerating to a minimum speed.

Another object is to provide means which will increase the speed of the motor to a maximum when the receiver pressure is below a predetermined low pressure.

Still another object is to provide means which 55 will decrease the speed of the motor to an intermediate speed when the receiver-pressure is between a' predetermined low and a predetermined intermediate pressure.

, It is a further object to provide means which will decrease the speed of the motor to a predetermined minimum speed when the'compressor is unloaded and maintain the motor at the predetermined minimum speed until the receiver pressure is dropped to a predetermined minimum pressure. m

It is a still further object to provide means which will vary the speed of the motor in accordance with the receiver pressure between a maximum and an intermediate speed as long as the receiver pressure does not exceed the predetermined high discharge pressure.

It is another object of the present invention to provide means whereby the compressor unit may operate at three predetermined speeds inaccordance with variations of the load and to maintain 2 corresponding rates of discharge fluid into the receiver.

These and other objects will be readily apparent in the following specification of which the drawings form a part. Similar numerals refer to similar parts in the drawing.

Figure 1 is a view in elevation illustrating the present invention as applied to a portable compressor unit.

Figure 2 is a view in section of the regulating device shown in Fig. 1, constructed in accordance with the principles of the present invention.

Fig. 1 illustrates a portable compressor unit which consists of a fluid compressor generally indicated at l driven by an internal combustion engine 3 mounted on a frame 5 supported by wheels 1.

Air is supplied to the compressor I through the conduit 9 and after being compressed passes through conduit l l to the receiver tank l3. Between the conduit 9 and the compressor l is placed an unloading device IS. The speed of the internal combustion engine 3 is regulated by the governor ll which is of a standard construction and, since it forms no part of the present invention, will not be described. The speed setting of the governor I1 is controlled by the speed governor regulator comprising a pressure responsive device or piston regulator device [9 and a means 2| to control the flow of receiver fluid thereto.

The piston regulator device l9 comprises a casing 23 with an internal bore 25-serving to guide the piston 21 within the casing. The bore 25 of the casing is closed at one end by the head 29. This head is threaded to receive the bushing 3| 5 locked in position by the lock nut 33. A passage 35 extends through the bushing and one portion thereof 31 is restricted to form the valve seat 39. The open end of the passage 35 is threaded to receive the conduit 4| which communicates with the receiver tank through the valve means 2| and the conduit 43 associated therewith.

Extending from either side of the piston 21 is a rod or plunger. One of these plungers 45 extends within the passage 35 of the bushing 3|. The end of this plunger 45 is shaped to form a valve 41 designed to coact with the valve seat 39 within the bushing 3| and to regulate the flow of fluid under pressure from the conduit 4| into the bore 25 of the casing 23. The other plunger 49 extends through the casing 23, as indicated by the dotted lines in Fig. 2, to a point without the casing.

The piston 21 is maintained in an intermediate position by the spring 5| so that when the unit is started the valve 41 will be open and permit the entrance of fluid under pressure within the bore 25. The spring 5| surrounds the bushing 3| and the plunger 45 and rests between the head 29 and the piston 21. Near the right hand end of the casing 29 a threaded passage is formed to receive the conduit 55. The purpose of this passage will be explained hereinafter.

In the lower part of the casing 23 is a vent passage 51 opening into the bore 25 near the left hand end of the casing. This passage terminates at its other end in an enlarged recess 59 containing a bushing 6|. Bushing 6| is formed with two recesses 53 and 65, connected by a passage 51, and the latter opens into an outlet 69 which, in turn, leads to the bore 1| in the casing 23. A conduit 13 is threadedly connected to bore 1| and extends through the wall of the casing 23 to the atmosphere. The recess 65 communicates directly with the conduit 15 and contains one ball check 11 of a ball check valve consisting of the ball check 11, a cylindrical portion 19, and a second ball check 8|. When the second ball check 8| rests in recess 63 to close'passage 51 no fluid can escape from the vent passage 51. The ball check 8| is lowered under certain operating conditions by the pressure of the fluid in vent passage 51 in order that fluid may escape through the conduit 13.

The plunger 49 extending from the piston is secured to a lever 83 outside of the casing which is fulcrumed at 85. 'A bolt 81, held in position by the lock nut 89, is fastened to a portion of the casing 23 and acts to limit movement of the lever 83 since this bolt overlies and, under certain conditions, contacts the ear 9| extending from the lever 83. The free end of the lever 83 is secured by a clevis connection to the rod 93 which is free to rotate about the pinion 95. The opposite end of the rod 93 is pivotally connected to the lever 91 by yoke 94 which, in turn, is pivotally mounted on the governor. The free'end of the lever 91 bears against the plunger 99 extending into the governor to control the compression of the governor spring (not shown).

Furthermore, the two levers IOI and I03 are designed to connect the governor I1 with the throttle valve I05 located in the intake manifold I01 of the internal combustion motor. When the governor speed setting is reduced by a release of the compression on the governor spring, these latter rods serve to move the throttle valve I05 toward the closed position and thus reduce the speed of the motor. Conversely, when the governor speed setting is increased by an increase of compression on the governor spring, the rods will move the throttle valve toward its open position and thereby increase the amount of fuel supplied to the motor, and, consequently, the speed of the motor.

Interposed between the receiver tank of the ,compressor unit and the piston regulator device I9 is the valve means 2| including a casing I09. A chamber III in casing I09 communicates with the receiver tank by means of the conduit 43 and the passage H3 at one end, and with the piston regulator device I9 by means of the conduit 4| and the passage I I5 on the other end. With this arrangement fluid under pressure in the receiver tank I3 may pass through the chamber II directly to the piston regulator I9.

On one side of the casing 2|, valve chambers H1 and I I9 are formed to receive the valves generally indicated at I2I. These valves are iden tical and, accordingly, only one valve will be described; the same reference numerals are used for both valves.

The valvechamber II1 opens directly into the chamber III through the port I23 which is normally closed by the valve proper I25 as it rests on the seat I21 to prevent the entrance of fluid under pressure from the receiver tank to the valve chamber. To maintain the valve I25 on its seat I21, a spring I29, surrounding the shank I3| of the member I33, is provided. The end of the valve chamber H1 is closed by a bushing I35 through which the shank I3I extends and this bushing is threaded to receive a second bushing I31 which is locked in position by the lock nut I39. The bushing I31 has a shoulder I4I against which the spring I29 rests. With this construction it is possible to adjust the compression of the spring I29 by turning the bushing I31 and in this way the pressure at which the valve I25 opens can be determined.

At one side of the valve chamber II1 is an opening I43 to which is attached the conduit 55. Similarly, the valve chamber II9 has an opening I45 designed to communicate with the conduit 15. In accordance with the principles of this in-' vention, the valve in the valve chamber H1 is designed to open at a different pressure from the pressure necessary to open the valve I25 in the valve chamber II9 as will be explained hereinafter.

The unloading mechanism. I5 placed at the inlet to the compressor consists of a casing I41 .closed by a plate I49. The casing I41 communimaintained between the cylindrical valve I55 and I the plate I49 normally holds the valve in its open or loading position at the right of the casing. In this position fluid may enter through the conduit 9 and flow around the ribs I59 to the conduit I5I.

At one side of the casing I41 is an opening to which is fastened the piston chamber I6I. The end of the chamber IIiI serves as a seat for the valve I55 when it is in its open position. Within the piston chamber and in slidable engagement therewith is a piston I63 whose movement is transmitted to the valve I55 by the shaft I65 formed as a part of the valve I55. The open end of the piston chamber I6I is closed by the plate I01 which has secured thereto the conduit 15.

Any fluid under pressure flowing in the conduit i5 willenter the piston chamber through the opening I69 furnished in the plate I61.

The operation of this regulating mechanism passage I 55, chamber III, passage H3 and con- I duit 53. The position of the piston 21 at starting is such that the plunger 49 will hold the lever 83 V in the intermediate position andthe speed setting of the governor I 1 is correspondingly at the intermediate speed. As the pressure in the receiver tank increases, however, the fluid pressure entering the bore 25 of the casing 23 will also increase and when the fluid pressure, acting on the face of the piston 21, is suflicient to overcome the governor spring tension, the piston will move to the right hand end of the bore 21 thus changing the governor speed setting to the maximum speed setting. The bolt 81 is used to predetermine the maximum speed at which it is desired to operate the unit, since it will act as a stop for the ear 9i of the lever 83 and once these two members have come in contact, further movement of the piston 27 toward the right is prevented. At the same time fluid under pressure enters the vent passage 51 and raises ball check 8| to the upper part of recess 63 where it prevents escape of fluid to conduit 13. As the ball 8I rises it raises cylindrical portion 19 and, consequently, ball 11 thus opening conduit 15 to atmosphere.

When the pressure in the receiver tank has increased to a predetermined intermediate pressure, it'is desirable to have the. governor speed decreased to an intermediate speed setting for economical operation. To this end the valve I2I in the valve chamber H1 is adjusted to open at this predetermined intermediate pressure which may be, for example, a pressure of 90 pounds per square inch. The intermediate speed is adjusted by changing the length of rod 93 by means of the yoke 94. at the end thereof. The spring 5I is stiff enough to withstand the push of th governor spring so that in adjusting the length of rod 93 the piston 21 can be considered as fixed and variation in the length of rod 93 will change the compression of the govemor spring. Upon the occurrence of a fluid pressure in the receiver tank of 90 pounds per square inch, the valve I25 in the valve chamber I I1 will open, thus permitting fluid under pressure to flow through the opening I23 into the conduit 55 and thence be led to the opening 53 in the casing 23 to admit fluid under pressure to the right hand side of the piston. The fluid pressure on this side of the piston will force the piston tothe left until the piston is stopped by the spring 5I. -Movement of the piston in this direction is possible because of the fact that the pressure on the opposite sides of the piston is the same since fluid enters opening 53 at the same pressure asthe fluid flowing by valve 41.- So long as the pressure in the receiver tank remains at approximately 90 pounds per square inch the compressor unit will continue to operate at the inter- 1 mediate speed. Meanwhile, since there is no fluid under pressure in conduit 15 the ball '8I still keeps the vent passage 51' closed to atmosphere.

Should the load on the unit decrease, however, the pressure in the receiver tank will increase. When the pressure reaches a predetermined maximum permissible pressure such as, for instance, 100 pounds per square inch, the valve I25 in valve chamber H9 which is adjusted so that it will open at 100 pounds per square inch, will open and allow fluid under pressure to enter the conduit 15 and flow to the unloading devic I5 to unload the compressor. At the same time the fluid will enter the recess 65 of the regulating mechanism I9 and force the ball 11 to its seating position. When the ball 11 assumes this position, it-forces the ball 8| to a lower position and allows fluid under'pressure to escape through the vent passage 51 to the conduit 13 which is designed to exhaust to atmosphere. Since the fluid in the bore 25 can escape from the portion of the chamber to the left of the piston faster than the fluid under pressure .can enter past the valve 41, the fluid under pressure entering through conduit 55 will force the piston 21 to overcome the spring 5I and. move to the left. Consequently, the plunger 45 will move to the left and bring the valve 41 to rest on its seat 31 to prevent further entrance of fluid under pressure through the conduit 4 I.

Movement ofthe piston to the left will move. plunger 49 and, consequently, the lever 83 will pivot about its fulcrum to move th governor spring to the minimum speed setting position. Since the minimum speed setting position is determined by the position of the piston 21, it is obvious that the position of the seat 39 controls the minimum speed of the governor. It is for this reason that the bushing 3I is threaded into the head 29 on the casing 23. The bushing may be moved to the right or left to determine the minimum speed position. Ashas been noted,'

the ball 8| is normally maintained in its upper or seated position by the fluid which enters the bore 25 through the conduit 4|. This will, of course, leave the conduit 15 open to atmosphere but. since under such conditions the valve in 'valve chamber H9 is closed, there will be no escape of fluid through the exhaust conduit 13. Furthermore, at the time that the valve in valve chamber H9 opens. flu d under pressure in conduit 15 is led to the piston chamber IGI and moves piston I63 to the left thereby moving the valve I55 to its unloading position.

The compressor will continue to operate in this manner until the pressure falls to pounds per square inch. At this pressure the valve in valve chamber H9 will close under the influence of spring I29. Upon closing this valve the unloading device will move to the right to reload the compressor. Any pressure existing in the conduit 15 will e cape to atmosphere through the passage Provided between the shank I3l and the bushing I31. The release'of this pressure will allow piston I53 to move to the ri ht and the spring I51 will push the valve I 55 to its right hand position.

At the sametime. the pressure on ball 11 will be released leavin the check member free to be raised and force the ball 8| to its seating position. 'Withthis set of conditions the speed setting of the governor,- however, remains the same since there is no fluid under pressure supplied through the conduit 4| to the piston 21 so long. as the valve 41 is on its seat 31. If the pressure continues to fall until it reaches, for example, 80 pounds per square inch, the valve I25 in valve chamber H1 will close. This permits any fluid under pressure in conduit 55 and any fluid'un der pressure in the bore 25 at the right of the piston to escape through the passage Provided between the bushing I31 and the shank HI.

As soon as this occurs the piston 21 will be free to move to the right under the influence of spring 5| and, consequently, open the valve 41. Fluid under pressure is then free to enter the bore 25 and to act on the left face of the piston to move it toward the right thus changing the speed setting of the governor to the maximum speed setting and allow thecompressor to run at its maximum speed. Thereafter the cycle will be repeated in accordance with the load demands on the compressor unit. a

If, for the sake of illustration, it be assumed that the valve I25 in valve chamber 1 opens at 90 pounds per square inch and closes at 80 pounds per square inch, the valve in valve chamber H9 opens at 100 pounds per square inch and closes at 90 pounds per square inch, the prede-' termined maximum speed setting of the governor is 1200 R. P. M. when the piston 21 is in its extreme right hand position, the intermediate speed is 860 R. P. M. with the piston 21 in its middle or intermediate position, and the governor speed is 60 R. P. M. with the piston 21 in its 25' extreme left hand position, unit will be as follows:

Upon starting the compressor, the unit will operate at 860 R. P. M. As the pressure increases in the receiver, the regulator piston 21 moves to its right hand position and the compressor will operate at 1200 R. P. M. When the pressure reaches 90 pounds per square inch, the valve in valve chamber H'I opens and permits the fluid under pressure to move the piston to the intermediate position so that the compressor 'will operate at 860 R. P. M. When the receiver pressure increases to 100 pounds per square inch, the valve in valve chamber H9 opens to permit .un-

the operation of the loading of the compressor and a reduction of G the engine speed to 600 R. P. M. If the pressure now falls to 90 pounds per square inch, the valve in valve chamber 9 closes thus reloading the compressor while the compressor speed re-' mains at 600 R. P. M. A further reduction in pressure to 80 pounds per square inch permits the closing of the valve in valve chamber H1 and a consequent opening of the valve 41 to allow the fluid in the receiver to move the piston to the right and increase the speed of the engine to 1200 R. P. M. The speed of the engine will soon decrease to 860 R. P. M., the intermediate speed, if the demand for air is not high.

I claim:

1. In a speed governor regulator for a fluid compressor unit, a pressure responsive device comprising a casing, a piston in the casing, a series of levers connecting the piston to the governor to transmit movement of the pistonto the governor and regulate the speed setting position thereof, a spring to normally hold the piston in an intermediate governor speed setting position, a valve associated with the piston to control the admission of compressor discharge fluid to the 75 2. In a speed governor regulator for a motor casing to move the piston to a maximum governor speed setting position, a second valve open-' ing in response to a predetermined intermediate compressor discharge pressure to admit compressor discharge fluid to" the casing to move the piston to an intermediate governor speed setting position, and a third valve openingin response to a predetermined maximum compressor discharge pressure and enabling the compressor discharge fluid to move the piston to the minimum governor speed setting position.

driven fluid compressor, a pressure responsive device having a piston and levers to transmit movement of the piston to the governor to regulate the speed setting thereof, means associated with the piston to regulate the admission of compressor discharge fluid to the pressure responsive device to move the piston to the maximum governor speed setting position, a second means acting in response to a predetermined compressor discharge pressure to admit compressor discharge fluid to the casing to move the piston to an intermediate governor speed setting position, and means acting in response to a second predetermined compressor discharge pressure enabling the piston to render the first means ineffective and to move to the minimum governor speed setting position.

3. In a speed governor regulator for a motor driven fluid compressor, a pressure responsive device having a piston and levers to transmit movement of the piston to the governor to regulate the speed setting thereof, means to unload and reload the compressor, means associated with the piston to regulate the admission of compressor discharge fluid to the pressure responsive device to move the piston to the maximum governor speed setting position, a second means act-- ing in response to a predetermined compressor discharge pressure to admit compressor discharge fluid to the casing to move the piston to an intermediate governor speed setting position, and means actingin'response to a second predetermined compressor discharge pressure to enable the unloading means to unload the compressor and the piston to move to the minimum governor speed setting position.

4. In a speed governor regulator for a fluid compressor unit, a. pressure responsive device comprising a casing, a piston in the casing, a pistonrod for the piston, a series of levers connecting the piston rod to the governor totransmit movement of the piston to the governor and regulate the speed setting of the governor, a valve sition, and a third valve adapted to open and en- .able compressor discharge fluid to move the piston to the minimum governor speed setting position and renderthe first valve ineffective.

5. In a speed governor regulator for a motor driven fluid compressor, a pressure responsive device actuated by the compressor discharge pressure arranged to set the governor at a maximum speed setting position in response to acompressor discharge pressure less than a predetermined intermediate dischargepressure and at a predetermined intermediate governor speed setting position in response to the' predetermined intermediate discharge pressure and at a predetermined minimum governor speed setting position in response to a predetermined maximum pressure and means controlling the flow of compressor discharge'fluid to the pressure responsive device.

6. In a speed governor regulator for a motor driven fluid compressor unit having a fluid receiver, a pressure responsive device connected to the governor, means to subject the pressure responsive device to the receiver fluid pressure to change the governor speed setting position to a maximum speed, means associated with the last said means adapted to cause the pressure responsive device to change the governor speed setting position to a predetermined intermediate governor speed setting position when the fluid pressure in the receiver reaches a predetermined intermediate pressure, and means associated with the first said means adapted to cause the pressure responsive device to change the governor speed setting position to a minimum speed when the fluid pressure in the receiver reaches a predetermined maximum pressure, all of said means coacting to maintain the governor speed setting position at a minimum speed until the receiver pressure reaches a predetermined minimum pres sure.

7. In a speed governor regulator for a motor driven fluid compressor unit having a receiver, means to control the speed setting of the governor actuated by the pressure of the fluid in the receiver, and means controlling the flow of fluid from the receiver to cause the first said means to assume three predetermined speed governor setting positions in response to'three respective predetermined receiver pressures.

8. In a speed governor regulator for a motor driven fluid compressor unit having a receiver, a pressure responsive device to control the speed setting of the governor actuated by the receiver pressure, means to subject the pressure responsive device to a low receiver pressure to set the governor at a predetermined maximum speed, means to subject the pressure responsive device to a predetermined intermediate receiver pressure to set the governor at a predetermined intermediate speed, means to subject the pressure.

responsive device to a predetermined highreceiver pressure to set the governor at-a minimum speed, the pressure responsive device in conjunction with the last said means being adapted to maintain the governor speed setting position at a minimum speed until the compressor receiver pressure falls to a predetermined minimum pressure.

9. In a speed governor regulator for a motor driven fluid compressor unit having a fluid receiver, a pressure responsive device adapted to regulate the speed setting of the governor, means to subject the pressure responsive device to receiver fluid pressure to change the governor speed setting to maximum. speed at a predetermined low pressure, and means'associated with the last said means to change the governor speed setting to a predetermined intermediate speed at a predetermined intermediate receiver fluid pressure and to a minimum speedat a predetermined maximum pressure and maintain the governor speed setting at minimum speed until a predetermined minimum receiver fluid pressure is reached.

10. In a regulator for a motor driven fluid compressor having a speed governor, a pressure responsive device to control the speed setting of the governor and having a maximum, intermediate and. minimum speed setting position, means to normally maintain the pressure responsive device at the intermediate speed setting position, means to admit compressor discharge pressure fluid to the pressure responsive device to cause the device to assume the maximum speed setting position, means to admit discharge pressure fluid to the pressure responsive device to cause the device to assume the intermedltae speed setting position 'upon a predetermined intermediate discharge pressure, and means to enable the dischargepressure fluid to cause the device to assume the minimum speed setting position.

11. In a speed governor regulator for a motor driven fluid compressor unit, means acting in response to the compressor discharge pressure to regulate the speed setting of the governor normally maintaining the governor speed setting at a predetermined intermediate speed, and means to subject the first means to a low compressor discharge pressure to change the governor speed setting to a maximum speed and to subject the first means to a predetermined intermediate pressure to change the governor speed setting to an intermediate speed and to subject the first means to a predetermined maximum discharge pressure to change the governor speed setting to a minimum speed and maintain the governor speed setting at minimum speed until a predetermined minimum discharge pressure is reached.

12. In a speed governor regulator for a motor driven fluid compressor unit, means responsive to the compressor discharge pressure to control the speed setting of the governor, means to control the flow of compressor discharge fluid to the first means, including means to admit fluid to the first means when the. pressure of the fluid does not exceed a predetermined intermediate pressure, a second means to admit fluid to the first means when the pressure of the fluid has reached a predetermined intermediate pressure until the pressure reaches a predetermined maximum pressure, and a third means to direct fluid to the first means when the pressure of the fluid is at a predetermined maximum pressure until the pressure reaches the predetermined intermediate pressure.i

13. In a speed governor regulator for a fluid compressor unit, a pressure responsive device comprising a casing, a piston in the casing, means to transmit movement of the piston to the governor to control the speed setting of the governor, means to normally hold the piston in the diate discharge pressure to cause the piston to set the governor at an intermediate speed setting position, and means responsive to 'a-predetermined maximum discharge pressure to cause the piston to set the governor at a minimum speed.

14. In-a speed governor regulator for a fluid compressor unit, means responsive to the compressor discharge pressure to change the speed setting of the governor, first means associated with the responsive means to subject the responsive means to the compressor discharge pressure to enable the responsive means to change the governor speed setting to the maximum speed setting position, .a second means to subject the responsive means to the compressor discharge. pressure to enable the responsive means to change the governor speed setting to an intermediate speed setting position, and a third means to direct compressor discharge pressure fluid to the pressure responsive means to enable the first said means to change the governor speed setting to a minimum speed setting position and to render the said first means inefiective.

15. In a speed governor regulator for a fluid compressor unit, means responsive to the compressor discharge pressure to change the speed setting of the governor, means to unload and re- 5 load the compressor, first means associated with the responsive means to subject the responsive means to the compressor discharge pressure to enable the responsive means to change the governor speed setting to the maximum speed setl ting position, a second means to subject the re-' sponsive J means to the compressor discharge pressure to enable change the governor speed setting to an intermediatespeed setting position, and a third means 15 to direct compressor discharge pressure fluid to the pressure responsive means to enable the first said means to change the governor speed setting to a minimum speed setting and to render the said first means inefiective and to subject 20 the unloading means to the compressor discharge pressure to unload the compressor.

16. In a speed governor regulator for a fluid compressor unit, means responsive to the compressor discharge pressure to change the speed 25 setting of the governor, means to unload and reload the compressor, a valve associated with the first means to control the flow of compressor discharge fluid thereto to move the pressure responsive means. to change the governor speed setting to the maximum speed setting position, a second valve responsive to a predetermined intermediate compressor discharge pressure to subject the pressure responsive device to the compressor discharge pressure and enable said 35 means -=to' change the governor sped setting to an intermediate speed setting position, and a third valve'responsive to apredetermined maximum compressor discharge pressure to supply discharge fluid to the unloading means to un- 40 load the compressor and to the pressure responsive .means to enable said means to change the governor speed setting to the minimum speed setting position.

11. In a speed governor regulator for a fluid 45 compressor comprising a casing, a piston in the casing, a piston rod for the piston, a series of levers connecting the piston rod to the governor to transmit movement of the piston to the governor to regu- 50 late the speed setting thereof, aospring to normally hold the piston in an intermediate speed setting position, a valve controlled by the piston to regulate the admission of compressor discharge fluid to the casing to move the piston to the max- 55 imum speed setting position, a second valve to admit compressor discharge fluid in response to a.

the responsive means to unit, a pressure responsive device,

predetermined discharge pressure to the casing on the opposite side of the piston to move the piston to the intermediate speed setting position, an exhaust conduit in the casing to remove compressor discharge fluid supplied through the flrst 5 said valve, a check valve normally rendering the exhaust conduit ineffective, and a third valve opening in response to a second predetermined pressure to enable compressor discharge fluid to actuate the check valve to open the exhaust conduit to enable the piston to move to the minimum speed setting position.

18. In a speed governor regulator for a fluid compressor unit, a device to unload and reload the compressor, a pressure responsive device comprising a casing, a piston in the casing, a piston rod for the piston, a series of levers connecting the piston rod tothe governor to transmit movement of the piston to the governor to regulate the speed setting thereof, a spring to normally hold the piston in an intermediate speed setting position, a valve controlled bythe piston to regulate the admission of compressor discharge fluid to the casing to move the piston to the maximum speed setting position, a second valve to admit compressor discharge fluid in response to a predetermined discharge pressure to the casing on the opposite side of the piston to move the piston to the intermediate speed setting position, an exhaust conduit in the casing to remove compressor discharge fluid supplied through the first said valve, 9. check valve normally rendering the exhaust conduit ineffective, and a third valve opening in response to a second predetermined pressure to enable the compressor discharge fluid to actuate the check valve to open the exhaust conduit to enable the piston to move to the minimum speed setting position and to actuate the unloading device to unload the compressor.

19. In a speed governor regulator for a motor a, driven fluid compressor, a pressure responsive device actuated by the compressor discharge pressure having a maximum governor speed setting position at a predetermined low discharge pressure, a predetermined intermediate speed setting position at a predetermined intermediate dis:

charge pressure and a minimum governor speed setting position at a predetermined maximum discharge pressure, and means associated with the pressure responsive device to direct the'flow of compressor discharge fluid to the pressureresponsive device to change the governor speed positions in response to said predetermined discharge pressures.

' CHARLES S. BAKER. as 

